/**
 * Copyright (C) 2001-2017 by RapidMiner and the contributors
 * 
 * Complete list of developers available at our web site:
 * 
 * http://rapidminer.com
 * 
 * This program is free software: you can redistribute it and/or modify it under the terms of the
 * GNU Affero General Public License as published by the Free Software Foundation, either version 3
 * of the License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
 * even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Affero General Public License for more details.
 * 
 * You should have received a copy of the GNU Affero General Public License along with this program.
 * If not, see http://www.gnu.org/licenses/.
*/
package com.rapidminer.tools.math.function.aggregation;

/**
 * Calculates the standard deviation.
 *
 * @author Tobias Malbrecht
 *
 */
public class StandardDeviationFunction extends VarianceFunction {

	public StandardDeviationFunction() {
		this(DEFAULT_IGNORE_MISSINGS);
	}

	public StandardDeviationFunction(Boolean ignoreMissings) {
		super(ignoreMissings);
	}

	@Override
	public String getName() {
		return "standard_deviation";
	}

	@Override
	public double getValue() {
		// return the square root of the variance
		double value = super.getValue();
		if (value > 0) {
			return Math.sqrt(value);
		}
		return 0d;
	}
}
